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Sorting arrays and hashes in Ruby

In Ruby, you can use the sort method on an array to sort that array - but you cannot sort a hash. That's because of the techniques used within a hash to make it very fast to look up individual elements.

So what do you do if you want to sort something like this: ?

stuff = {"Steve" => "Kent", "Graham" => "Wiltshire",
  "Chris" => "Wiltshire", "Betty" => "Windsor",
  "Fred" => "Aberstwyth", "Harry" => "Potteries",
  "Sarah" => "Wiltshire"}

You get an array of the keys (using the keys method on the hash), and then you sort the list. To output the pairs from the hash in order, you step through the hash in the order given in the list and the job is done!

There's an example [here] in the examples directory - a piece of code I wrote as a demonstration during this week's Ruby Programming Training Course.

(written 2010-01-30)

Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
R107 - Collections (Arrays and Hashes) in Ruby
  [4502] Reading and parsing a JSON object in Ruby - (2015-06-01)
  [4499] Significant work - beyond helloworld in Ruby - (2015-05-27)
  [4368] Shuffling a list - Ruby and Python - (2014-12-28)
  [3757] Ruby - a teaching example showing many of the language features in short but useful program - (2012-06-09)
  [3435] Sorta sorting a hash, and what if an exception is NOT thrown - Ruby - (2011-09-12)
  [3257] All possible combinations from a list (Python) or array (Ruby) - (2011-04-23)
  [3255] Process every member of an array, and sort an array - Ruby - (2011-04-21)
  [3253] Is this number between? Does this list include? - Ruby - (2011-04-18)
  [2976] Creating, extending, traversing and combining Ruby arrays - (2010-09-30)
  [2621] Ruby collections and strings - some new examples - (2010-02-03)
  [2618] What are Ruby Symbols? - (2010-02-02)
  [2291] Collection objects (array and hash) in Ruby - (2009-07-16)
  [991] Adding a member to a Hash in Ruby - (2006-12-16)

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This is a page archived from The Horse's Mouth at http://www.wellho.net/horse/ - the diary and writings of Graham Ellis. Every attempt was made to provide current information at the time the page was written, but things do move forward in our business - new software releases, price changes, new techniques. Please check back via our main site for current courses, prices, versions, etc - any mention of a price in "The Horse's Mouth" cannot be taken as an offer to supply at that price.

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